niche != small market

I confused the concept of niche in entrepreneurship with the small market. They are not the same.

There is no problem if the small market size is enough to build a monopoly or if it has signs of growth. Otherwise, I should pick the niche in a vast market and then expand.

I chose a screenshot API as the first project with which I want to make money. But the market seems to be too small and has a lot of decent players. Anyway, it is a good challenge to tackle by itself. What options do I have?

1. Be the top player in the market to acquire customers.
2. Add features related to image processing and screenshots.
3. Start building more APIs and expand into the marketplace? It is probably not possible since the current project has its precise branding for taking screenshots.

I will try to make the top solution and add features related to screenshots. And then, I can build a separate API marketplace that integrates screenshot API.

For the following projects, I must learn about the market I will jump in.